The purpose of air conditioning and ventilation systems in buildings and transportation vehicles is to supply persons in the buildings or vehicles with clean, fresh temperature controlled air. One reason for air conditioning and ventilation systems is to ensure that each person in an enclosure inhales air with acceptable air pollutant levels. Since people might be at different positions inside a building or vehicle, it is necessary to re-circulate and condition all the air in the whole building or vehicle passenger compartment. Typical ventilation systems are designed to re-circulate, filter and control the temperature of all the air in the building or vehicle. Outlets delivering fresh air to the building or vehicle may be quite distant from persons in the building or vehicle. For example, the ventilation outlets in offices, cinemas, musical halls, planes, ships, trains, buses, etc. are typically located on the ceiling or roof of the structure. The air from the outlet will mix with dust and pollutants in the room before reaching people, so the quality of the air inhaled by people in the room is worse than the quality of air from the outlets.
A personal air conditioner system, having a plurality of outlets aimed at every user used in offices, has been disclosed in U.S. Pat. No. 6,318,113 B1 (the '113 patent). The system outlets are illustrated as positioned in the floor, desk or walls a distance of at least approximately two feet from the person's nose and mouth. The ventilation system is inefficient because directing airflow in different directions will not further overall movement of air and waste energy. The distance between the ventilation outlets and the people in the room permits optimal air from the outlets to mix with dust and other pollutants in the room. The system disclosed in the '113 patent is inefficient because it cools (or heats) indoor objects by contact, e.g., walls, glazing, ceilings, bulbs etc. These are typically objects which should not be cooled (or heated) will also be cooled (or heated). Energy is wasted on this unnecessary cooling (or heating).
An air conditioning device installed on the back of the chairs in a cinema has been disclosed in U.S. Pat. No. 4,035,018. (the '018 patent). The '018 patent ventilation system outlets overcome the deficiency of mixing indoor air compared with the '113 patent, but the outlet are still too far from the nose and mouth of those seated in the chairs. The '018 patent also discloses an air inlet about a foot from the floor at every air supply duct. An air intake in this position will draw in dusts and other pollutants from the floor. These pollutants will be delivered through the ventilation system. Thus it can be seen that however optimal the air from existing ventilation systems might be, if the ventilation outlets are positioned a significant distance from the breathing zone (nose and mouth) of occupants, the air delivered to the occupants is mixed with polluted indoor air.
The American Society of Heating Refrigerating and Air conditioning Engineers (for short hereinafter, ASHRAE) promulgates a rate of outdoor fresh air intake of around 10 liters/second/person to ensure an acceptable indoor air quality. This is far in excess of the actual the human respiration rate for fresh air, which is around 0.1 liters/second/person. In other words, the existing ventilation systems and accepted rates of fresh air intake are approximately 100 times greater than would appear necessary (namely, the utilization efficiency is only 1%). This means that much more air is heated (or cooled), filtered, disinfected (e.g. using UV radiation), deodorized, humidified (or dehumidified) and moved than would be necessary with more efficient delivery systems. As a result, tremendous quantities of energy are wasted.
Further, people sitting in a restricted space (e.g., planes, ships, trains, coaches etc.) for a long time, may have to suffer with unpleasant odors produced by their fellow occupants. These may include smoke (even in non-smoking sections), body odor, and food odors (such as civet durian or fish). Some restrictions on occupant behavior such as no smoking, no eating, no taking off shoes have been imposed to minimize odors that may disturb others. However, such restrictions can make occupants uncomfortable, and still not prevent the unseen and imperceptible spread of pathogens (such as virus of influenza and tuberculosis bacteria). This is a serious concern given the recent epidemic of several new respiratory diseases.